Method of manufacturing a board

Abstract

Methods of manufacturing board products include the steps of drying lignocellulosic material in a first stage dryer, further drying the lignocellulosic material in a second stage dryer, forming the dried lignocellulosic material into a mat, hot pressing the mat, utilizing the pressed air stream from the hot pressing step and a supply of fresh air as the source of drying air for the first and second stage dryers, utilizing the exhaust air from the second stage dryer as a source of drying air for the first stage dryer, and utilizing the exhaust air from the first stage dryer as a source of drying air for the first stage dryer and as a source of combustion air in a furnace.

We claim: 
     
       1. A method for manufacturing board product from lignocellulose-containing material comprising drying said lignocellulose-containing material in a first dryer stage in the presence of a first supply of drying air to produce a dried lignocellulose-containing material and a first supply of exhaust air, further drying said lignocellulose-containing material in a second dryer stage in the presence of a second supply of drying air to produce a further dried lignocellulose-containing material and a second supply of exhaust air, forming said further dried lignocellulose-containing material into a mat, hot pressing said mat thereby producing a press air stream therefrom, combining and utilizing said press air stream and a supply of fresh air as a source of said first and second supplies of drying air, utilizing said second supply of exhaust air as a source of said first supply of drying air, and utilizing said first supply of exhaust air as a source of said first supply of drying air and as a source combustion air in a furnace. 
     
     
       2. The method of claim 1 including producing flue gas from said furnace, and heating said first and second supplies of drying air with said flue gas. 
     
     
       3. The method of claim 1 including reheating said first supply of exhaust air, and utilizing said reheated first supply of exhaust air as primary air in said furnace. 
     
     
       4. The method of claim 1 including utilizing at least part of said first supply of exhaust air directly as secondary air in said furnace.